H-fluid as an alternative to HFC-134a?
The new European Directive 2006/40 on emissions from air-conditioning systems in motor vehicles - which bans F-gases with a GWP higher than 150 (such as HFC-134a) as of 2011 for new models of cars - and Californian legislation which is putting pressure on the industry for HFC-134a phase-out have led refrigerant producers DuPont and Honeywell to try to develop new alternative refrigerants, in parallel to intensive R&D currently led on CO2. Honeywell recently gave further information on the new "H-fluid" that it is currently testing in co-operation with Valeo. It is an azeotropic blend of a newly created molecule called 1,1,1,2 tetrafluoropropene combined with a recently introduced chemical, trifluoromethyl iodide, with thermodynamic properties (boiling point, critical point, flammability) very similar to those of HFC-134a. The GWP of this new fluid should be about 10. The major advantage would be the ability to replace HFC-134a with only minor system modifications. Recent performance tests showed cooling capacity and COP with H-fluid similar to those with HFC-134a at medium and low thermal loads (ambient temperature of 15°C-35°C) and a little lower at higher loads. Validation programmes (particularly on toxicity) have to be run before a final decision on feasibility expected at the end of next year.